1. Technical Field
The present invention relates to an image recording apparatus for detecting the tension of a recording medium on the basis of a force received by a roller from the recording medium.
2. Related Art
An image recording apparatus in Japanese laid-open patent publication No. 2013-129062 is equipped with a configuration where a sheet that is wound up into the shape of a roll is supported with a roller that is provided between a feed-out spindle and a take-up spindle, while both ends of the sheet are also being supported at the feed-out spindle and the take-up spindle. In particular, with the image recording apparatus of such description, a driven roller around which the sheet, having been fed out from the feed-out spindle, is wound is responsible for a steering function for adjusting the position of the sheet in the axial direction of the feed-out spindle as well as a tension detection function for detecting the tension of the sheet. In other words, this driven roller is configured so as to be movable in the axial direction of the feed-out spindle, and adjusts the position of the sheet in the axial direction of the feed-out spindle by moving in the axial direction of the feed-out spindle in accordance with the position of detection of a sheet end. Attached to this driven roller is a tension sensor constituted of a load cell; by detecting the force received from the sheet, the tension sensor detects the tension of the sheet.
In order to use the tension sensor attached to the roller to accurately detect the tension of the sheet, as described above, it is important that the force received by the roller from the sheet be sufficiently transmitted to the tension sensor. To elaborate on the reason for this, the force transmitted to the tension sensor from the roller changes when there is a change in the force received from the sheet by the roller, in accordance with a change in tension of the sheet. Thus, the result of detection of the tension sensor is reflective of the change in tension of the sheet. As such, in order to accurately detect the tension of the sheet, it is important that the force received from the sheet by the roller be sufficiently transmitted to the tension sensor and be reflected well in the result of detection of the tension sensor.
However, a support member by which the roller by which the roller is driven in the axial direction while also being supported is in some instances separately provided in an image recording apparatus where the roller is moved in the axial direction with the aim of having the roller also fulfill a steering function or the like, as described above. Such an instance gives rise to the possibility that the force received by the roller from the sheet will be distributed to the support member and will not be sufficiently transmitted to the tension sensor, because the support member supports the roller against the force received from the sheet, thus making it impossible to accurately detect the tension of the sheet.